Forging method and apparatus



May 1, 1956 Filed Dec. 7, 1950 S. BERG FORGING METHOD AND APPARATUS 8 Sheets-Sheet l Zhwentor (Ittorneg May 1, 1956 s. BERG 2,743,500

F ORGING METHOD AND APPARATUS Filed Dec. 7, 1950 8 Sheets-Sheet 2 Zhwentor May 1, 1956 Filed Dec. 7, 1950 ll/\T A I 1 X P x= 1. (I 60am) Y: L/anv. AA)

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s. BERG 2,743,500

FORGING METHOD AND APPARATUS 8 Sheets-Sheet 3 May 1, 1956 s. BERG 2,743,500

FORGING METHOD AND APPARATUS Filed Dec. 7, 1950 8 Sheets-Sheet 4 May 1, 1956 s. BERG 2,743,500

FORGING METHOD AND APPARATUS Filed Dec. '7, 1950 8 Sheets-Sheet 5 Jnventor (Ittomeg May 1, 1956 s, BERG 2,743,599

FORGING METHOD AND APPARATUS Filed D80. 7, 1950 8 Sheets-Sheet 6 Elli g gQ 3/ 32 I w H 3/ I Snuentor W Clttomcg May 1 1956 Filed Dec. 7, 1950 s. BERG 2,743,500

FORGING METHOD AND APPARATUS 8 Sheets-Sheet 7 lhwcntor Gttorncu May 1, 1956 Filed Dec. '7, 1950 s. BERG 2,743,500

FORGING METHOD AND APPARATUS 8 Sheets-Sheet 8 Zhwentor United States Patent FORGING METHOD AND APPARATUS Sverre Berg, Erie, Pa., assignor to Erie Forge Company, Erie, Pa., a corporation of Delaware Application December 7, 1950, Serial No. 199,710

16 Claims. (Cl. 29-5 This invention is intended to forge crank shafts by a method in which the geometrical center line of the ingot or billet will follow the neutral axis of the finished crank shaft. In carrying out the method, a billet is gripped between dies at the points at which the journals are to be formed, and the central portion of the billet between the journals from which the crank pin is to be formed is offset by a hydraulically operated pin forming die. Simultaneously with the offsetting, the journal dies are hydraulically moved toward each other, and at a rate related to the movement of the pin die such that the neutral axes of the portions of the billet which are to form the crank webs is neither stretched nor compressed. At the end of the offsetting or bending operation, the neutral axes of all portions of the billet are centered and the neutral axes of the web portions of the billet extend at an angle to the center line of the crank shaft of less than 90, typically an angle of from 45 to 60 degrees, depending upon the crank throw. In this position the neutral axis of the billet has been neither stretched nor compressed but assumes a natural position and the journals are spaced apart further than in the finished crank and the webs have not been flattened. The flattening or forging of the webs is accomplished by moving the journal dies toward each other under full hydraulic pressure. These dies cooperate with the pin dies to form closed dies which forge the webs to the desired shape so that subsequent machining is minimized. During the flattening or forging of the webs, the neutral axis of the billet moves to a position at the center of the webs with smooth fillets merging into the neutral axes of the journals and crank pin.

The apparatus for performing the forging method comprises horizontal and vertical presses with an interrelated control such that the bending of the forging billet to offset the pin does not stretch the neutral axis of the billet. Further objects and advantages appear in the specifica tion and claims.

In the drawings, Fig. l is a side elevation of a single crank, Fig. 2 is a section through the pin and journal dies showing the billet at the start of the forging operation, Figs. 3, 4 and 5 show the successive offsetting or bending steps forming the crank pin, Fig. 6 shows the position of the journal dies at the end of the forging of the webs, Fig. 7 is a diagram showing the position of the center line or neutral axis of a web portion of the billet in successive positions from the start to the completely forged crank, Fig. 8 is a sectional elevation of the pin and journal dies at the start of the offsetting, Fig. 9 is a diagram showing the relation between the travel of the horizontal and vertical presses and the length of the web forming portions of. the billet, Fig. 10 is a diagram of a cam controlling the movement of the horizontal presses, Fig. 11 is a plan of the horizontal presses which act together, one on each side of the journal dies, Fig. 12 is an end view, partly in section, of the horizontal presses, Fig. 13 is a side elevation of the vertical press including an end view. of the horizontal presses, Fig...14..is.a side elevation of one of the horizontal presses, Fig. 15 is a fragmentary end view of one of the horizontal press cylinders, and Fig. 16 is a side elevation partly in section, of two of the horizontal press rams.

In the finished crank as shown in Fig. 1 there are journals 1, a crank pin 2 and webs or throws 3. The crank is formed from a billet 4 of a diameter slightly larger than the diameter of the main hearings in the crank shaft to be formed, and having a neutral axis 5 along the center line. In the forming or forging operation it is desirable that there be a minimum of disturbance of the fiber of the metal. The position of the neutral axis in the completed crank is indicated in Fig. 1, the reference numerals 6 indicating the neutral axes of the journals, the reference numeral 7 indicating the neutral axis of the crank pin and the reference numeral 8 indicating the neutral axes of the crank webs or throws. It will be seen that in the finished crank the neutral axes 6 and 7 are on or parallel to the axis of the crank shaft and that the neutral axes 8 are in general perpendicular to the axis of the crank shaft and have fillets 9 and 10 merging into the neutral axes 6 and 7. With this flow line arrangement, the neutral axis 5 of the forging billet has been re arranged so that it follows the neutral axis of the finished crank shaft, and there is an absence of abrupt changes in direction at which points of weakness might develop. A further characteristic, as will hereinafter appear, is that the neutral axis of the forging billet is not subjected to substantial stretching, compression or shearing during the forging operation.

The forging of the crank is performed by dies arranged as shown in Fig. 8. The lower halves 11 of the journal forming dies are slidably carried on guides 12 on a bed 13. The upper halves 14 of the journal dies are slidably car-- ried in a cross head 15 which is moved downward by a piston 16. The dies 14 are both Vertically slidable in guides 17 which are moved horizontally toward each other by rams 18. The guides 17 have the function of carrying the overhung weight of the pintles 35 to prevent them from exerting excentric loading on the packing for rams 18. The piston 16 exerts sufficient pressure so that when the diesll and 14 are closed, the portion of the billet forming the journals is forged.

The cross head 15 carries the upper half 19 of a crank pin forming die. The lower half 20 of a crank pin forming die is carried by a piston 21 in the bed of the press. At the start of the forging operation the piston 21 is in such a position that the billet lies on the lower halves l1 and 20 of the journal and pin dies. After the journal dies 11 and 14 are closed the piston 21 moves the pin die 20 upward until it mates with the upper pin die 19 thereby forging the crank pin. The speed at which the piston 21 moves is not critical. Ordinarily the piston 21 moves at a fixed speed. Simultaneously with the upward movement of the piston 21 there is an endwise movement of the rams 18 sliding the journal dies 11 and 1 5 horizontally toward each other. The endwise movement of the rams 18 is so related to the upward movement of are neither stretched nor compressed. This is clearly shown in Figs. 2 to 5 which show the position of the forging billet at successive stages of the forging operation.

Fig. 2 shows the position of the billet when the journal dies 11, 14 have been closed to form the journals. At this point there has been no upward movement of the piston 21 and the billet rests in the lower half 20 of the pin forming-die. As the piston 21-starts its upward travel there is only a slight endwise movement of the rams 18. The endwise movement of the rams 18 is such that the distance between points 22 and 23 along the centenline, of. the billet remains constant. As the upward movement of the piston 21 continues the rate of endwise movement of the rams 18 increases and reaches its maximum rate at the position illustrated in Fig. in which further upward movement of the piston 21 is stopped by the closure of the pin dies 19, 20. It will be noted that the distance between the points 22 and 23 along the center line of the billet is the same in Figs. 2, 3, 4 and 5 thereby indicating that the center line or neutral axis of the billet has been neither stretched nor compressed during the forging of the pin and the bending of the web forming portions of the billet. Because the pin forming dies 19, close only at the uppermost position in Fig. 5, the web and pin forming portions of the billet have the greatest possible freedom to assume a position of. minimum strain or fiber deformation. In the position shown in Fig. 5, the web forming portions of the billet, namely the portions between points 22 and 23, are. accordingly in an ideal condition for flattening. In this position however, the neutral axis does not extend at the proper angle which ideally would be at. 90 to the axis on the crank. While the angle of the neutral axis in. the Fig. 5 position will vary with the crank throw it ordinarily is in the region of from 45 to 60 degrees.

Upon reaching the Fig. 5 position, the piston 21 is stopped by the closing of the dies 19, 20. From this point on, the rams 18 move endwise toward each other at maximum pressure and for a sufiicient distance to perform the flattening or forging of the webs. This horizontal movement continues until dies 11 and 14 butt up against pin dies 19 and 20, insuring proper lengthwise spacing of the throws on a multiple throw crank shaft. The webs are between the end faces of the pin and journal dies which have recesses 24 and 25 forming the outer and edge surfaces of the webs as the journal dies close on the pin dies. The recesses 24 in the lower pin die 29 forms the lower inside surface of the Webs and the lower edge surfaces up to the center line of the journals. The recess 25 in the journal dies 14 form the upper outside and edge surfaces of the webs down to the center line of the journals. The flash, which must be present if the recesses are to be completely filled, occurs at the ends of the pin die 19 between the end surfaces of the pin die and the journal dies 14. This is at a point Where machining is required so that hash is removed in the machining operation. At the end of the forging operation as shown in Fig. 6, the webs 3. are formed to finished shape in closed forging dies defined by the recesses 24 and 25. When the metal flows into the recesses 24 and 25 there is formed the smooth fillets 9 and 10 connecting the neutral axis 8 of the finished web with the journal and. pin neutral axes 6 and. 7. From the point of view of the neutral axis the flattening of the web forming portions of the billet amounts to the bending of the neutral axis to a position at right angles to the axis of the crank shaft and a forming of fillets at the points of connection to the neutral axes of the journals and crank pin.

in Fig. 7, the neutral axes of the web forming portion of the billet are superimposed. As the journal: dies are moving from the Fig. 2 to the Fig. 5 positions, the travel of the journal dies is controlled with reference to the travel of the lower pin die so that the neutral axes of the web forming portion of the billet are neither flattened nor compressed but are merely bent at an angle assuming a natural position of minimum fiber deformation. The necessary relation between the travel of the journal dies and the lower pin die is brought out in Fig. 9. In this figure x is equal to the travel of the journal dies and "y equals the travel of the lower pin die. If the length of the neutral axis of the web forming portions of the billet is to remain constant throughout the offsetting of the crank pin, it will appear that the speed of the journal die travel will have to equal the speed of the lower pin die travel times the tangent of the angle between the neutral axis of the web and the neutral axis of the journal. This expression mathematically would be (It dt Fig. 10 shows a control for producing this relation between the journal and pin die travels. In this figure 27 is a cam carried by one of the journal dies and 28 is a microswitch controlling the horizontal movement of the journal dies carried by the lower pin die 20. The microswitch has a cam follower 29 on an arm 29a which is shown in the stopped position of the journal dies. As the microswitch 28 moves up with the lower pin die 20, the cam follower 29 drops and starts the movement of the journal dies toward each other. This endwise movement stops when the cam 27 carried by one of the journal dies 11, 14 moves inward enough to return the microswitch to the position illustrated. Since the shape of the cam 27 is developed from the relationship shown in Fig. 7, the motion of the journal dies is so controlled that the neutral axes of the webs are not stretched during the movement from the Fig. 2 to Fig. 5 positions. At the Fig. 5 position, the cam follower 29 of the switch 28 rides on the flat surface 27a of the cam 27, and the journal dies move toward each other until journal dies 11 and 14 close against pin dies 19 and 20 insuring proper lengthwise spacing of the throws. The endwise closing movement of the journal dies continues immediately following the Fig. 5 position until the desired upsetting or flattening of the webs is obtained. There are other controls for obtaining this relation between the die travels. It is also possible to control the dies manually.

Figs. 11-16 show further details of the two horizontal presses for moving the journal dies endwise of the crank shaft and of the vertical press for closing the journal dies and for raising the lower pin die 20.

. Each of the horizontal presses has eight cylinders 30, four at each end arranged one above the other so that two of the. cylinders act on each half of the journal dies. The cylinders 30 are bored in pairs in the inner end of a frame 31. The reaction force of each pair of cylinders is taken by a strain rod 32 adjacent the cylinders 30 and by a compression rod 33 connected to the outer end of the frame, Compression rods 33 are necessary because the cylinders 30 are offset on one side of the strain rods 32 so the reaction force tends to pivot the frame about the tension rods 32. At each end ofv the horizontal press, there are two frames 31 arranged one on top of the other. The outer ends of the frames 31 are connected by distance rods 34. As shown more clearly in Fig. 16, the pressure from each of the rams 18 is transferred to the guides 17. by means of a pintle 35 having a ball and socket connection 36 with the ram and a ball and socket connection 37 with the guide. The guide 17 as shown in Fig. 14, is made in upper and lower halves connected by a hinge pin 38. With this construction, the guides assume a pressure equalizing position in the journal dies 11, 14 and the rams 18 have a pressure equalizing connection with the guides.

By having the two horizontal presses control endwise sliding of the journal dies 11, 14 arranged so that one press acts at each side of the journal dies as shown in Fig. 13, the center is unobstructed so that a forging billet can be easily loaded between the horizontal presses. This is advantageous in forging multiple throw crank shafts each crank of which is to be forged separately and. at the proper angle so as to eliminate the need for twisting operations following the forging. As shown in Fig. 13, the strain rods 32 for the horizontal presses tit in the space between the journal dies 11, 14 and the strain rods 39 for the vertical press which forms the crank pin. Since the journal dies are guided at both top and bottom and are subjected to equalized pressure from the vertical guides 17 the journal dies remain in alignment throughout the movement by the horizontal. presses. Thereis no need for separate controls for the two hori zontal presses since each press is constrained to follow the other by the journal dies.

What I claim as new is: r

1. The method of forging a crank shaft from a billet having a portion to be formed into a crank pin, portions laterally spaced from each end thereof to be formed into journals, and intermediate portions connecting the pin and journal portions to be formed into webs or crank throws which comprises, gripping the journal portions of the billet between journal forming dies under pressure crosswise of the journal, engaging the inner surface of the pin portion of the billet with the lower half of a pin forming die and moving the same in the direction to offset the pin portion and toward the upper half of a pin forming die while simultaneously maintaining the grip ping pressure on the journal dies and moving the journal dies toward each other at a rate such that the distance between the adjacent ends of the pin and journal portions of the crank along the center line of the billet remains constant during forging whereby the neutral axes of the web portions between the journal and pin dies are substantially neither stretched nor compressed, the lower half of the pin die closing against the upper half of the pin die at the end of the offsetting to form the pin, and then moving the closed journal dies toward each other to flatten the web portions of the billet.

2. The method of forging a crank shaft from a billet having a portion to be formed into a crank pin, portions laterally spaced from each end thereof to be formed into journals and intermediate portions connecting the pin and journal portions to be formed into webs or crank throws which comprises, closing split journal forming dies on the journal forming portions of the billet under pressure crosswise to the axis of the shaft, engaging the under side of the pin forming portion of the billet with one half of a pin forming die and moving the pin die in the direction to offset the pin and toward the other half of the pin forming die while at the same time maintaining the closing pressure on the journal dies and moving the journal dies toward each other at a rate such that the distance between the adjacent ends of the pin and journal portions of the crank along the center line of the billet remains constant during forging whereby the neutral axes of the intermediate web portions of the billet are substantially neither stretched nor compressed, said pin die closing at the end of the offsetting movement to forge the pin, said pin and journal dies having recesses in the end faces thereof forming the sides of the Web, and then moving the closed journal dies toward each other under forging pressure to cause the web portions of the billet to fill the recesses and thereby form the webs or crank throws.

3. Apparatus for forging crank shafts comprising a vertical press having a cross head carrying the upper half of a pin forming die intermediate the upper halves of journal forming dies, guides in the cross head and journal dies permitting sliding of the journal dies toward the pin die, a bed slidably carrying the lower halves of the journal dies, and a ram carrying the lower half of the pin die, and a pair of horizontal presses, said presses being laterally spaced apart so as to exert forces on spaced horizontal axes and arranged so the axes are respectively at each side of the axis of the journal dies and said presses having rams engaging the outer ends of the journal dies for moving the same toward each other and having strain members extending along the outside of the journal and pin dies, whereby the space along the axis of the crank shaft is unobstructed.

4. Apparatus for end and crosswise forging of crank shafts comprising a vertical press having a bed slidably carrying the lower halves of journal dies for movement toward each other, a cross-head slidably carrying the upper halves of journal dies for movement toward each other and carrying an intermediate die forming the upper surface of a crank pin, a piston for moving the crosshead downward to close the journal dies, a ram carrying the lower half of the pin forming die, the pin and journal dies being shaped to close against each other and having recesses therein forming the webs or crank throws, and a pair of horizontal presses, said presses being laterally spaced apart so as to exert forces on spaced horizontal axes and arranged so the axes are respectively one at each side of the axis of the journal dies and respectively acting on the outer ends thereof to move the journal dies toward each other and close the same against the crank dies, said horizontal presses having strain members extending outside the journal dies whereby the region along the axis of the crank shaft is unobstructed.

5. The method of forging crank shafts from a billet having portions from which are to be formed the journals,

crank pin and crank throws or webs which comprises gripping the journal portions of the billet between journal forging dies forced together against the journal portion of the billet under a force transverse to the billet, bending the web portions of the billet without stretching or compressing the central axes thereof by oifsetting the pin portion of the billet while moving the journal dies toward each other at a rate maintaining constant the length of the central axes of the web portions and maintaining the pressure on the journal dies, forging the crank pin at the end of the web bending operation between crank pin dies forced against the pin portion of the billet under a force transverse to the axis of the crank pin, and thereafter forging the webs between web forming dies in the journal and pin dies under pressure endwise of the shaft.

6. The method of forging a crank shaft from a billet having a portion to be formed into a crank pin, portions laterally spaced from each end thereof to be formed into journals, and intermediate portions connecting the pin and journal portions to be formed into webs or crank throws which comprises, gripping the journal portions of the billet between journal forging dies forced together against the journal portions of the billet under a pressure transverse to the billet, bending the web portions of the billet by a pressure exerted only on the inner surface of the pin portion of the billet while moving the journal dies toward each other at a rate maintaining constant the length of the central axes of the web portions and maintaining the pressure on the journal dies, forging the pin at the end of the bending of the web portions of the billet between dies forced together under a pressure transverse to the pin portion of the billet, and then flattening the bent web portions of the billet to form crank throws.

7. The method of forging a crank shaft from a billet having a portion to be formed into a crank pin, portions laterally spaced from each end thereof to be formed into journals, and intermediate portions connecting the pin and journal portions to be formed into webs or crank throws which comprises, gripping the journal portions of the billet between journal forming dies under pressure crosswise of the journals, bending the web portion of the billet to offset the pin portion of the billet while the pin portion is unconfined and the journal dies are moved toward each other at a rate maintaining constant the length of the neutral axes of the web portions of the billet while maintaining the gripping pressure on the journal dies, gripping the pin portion of the billet between pin forming dies at the end or" the web bending operation, and then flattening the bent web portion of the billet to form crank throws.

8. Apparatus for end and crosswise forging of a crank shaft from a billet having a portion to be formed into a crank pin, portions laterally spaced from each end thereof to be formed into journals, and intermediate portions connecting the pin and journal portions ot be formed into webs or crank throws, comprising pairs of journal dies split along a plane extending through the center line of the journal and spaced from the pin, said dies being recessed to form the outer and edge surfaces of the crank throws from the pin down to the center line of the journal, a pair of pin dies split along a plane extending through the center line of the pin and spaced from the journals, said dies being recessed to form the inner and edge surfaces of the crank throws up to the center line of the journals, means for closing the dies on the journal and pin portions of'the billet and for offsetting the pin with respect to the journals, and means for moving the closed journal dies toward the pin dies to form the webs or crank throws by upsetting the web portions of the billet into said recesses.

9. Apparatus for end and crosswise forging of a crank shaft from a billet having a portion to be formed into a crank pin, portions laterally spaced from each end thereof to be formed into journals, and intermediate portions connecting the pin and journal portions to be formed into webs or crank throws, comprising pairs of upper and lower journal dies split along the center line of the journal and having the upper die of each pair recessed to form the outer and edge surfaces of the crank throw from the pin down to the center line of the journal, a pair of upper and lower pin dies split along the center line of the pin and having the lower pin die recessed at each end to form the inner and edge surfaces of the crank throws up to the center line of the journals, means for closing the dies on the journal and pin portions of the billet and for offsetting the pin with respect to the journals, and means for moving the closed journal dies toward the pin dies to form the webs or crank throws by upsetting the web portions of the billet into said recesses.

' 10. Apparatus for end and crosswise forging of a billet comprising two pairs of dies spaced apart endwise of the billet, each pair comprising dies separable to receive a billet therebetween, and one pair being movable toward the other pair endwise of the billet to upset the same, a crosswise press for closing the dies, and a pair of endwise presses, said presses being laterally spaced apart so as to exert forces on spaced axes extending endwise of the billet and arranged so the axes are respectively on each side of the endwise movable pair of dies for moving said endwise movable pair of dies toward the other pair to upset the billet.

11. Apparatus for end and crosswise forging of a billet comprising two pairs of dies spaced apart endwise of the billet, each pair comprising dies separable to receive a billet therebetween, and one pair being horizontally movable toward the other pair endwise of the billet to upset the same, a vertical press having a crosshead carrying one of each pair of dies, a guide on the crosshead for the horizontally movable die, a guide on the press for the other horizontally movable die, vertical guides at each side of the horizontally movable dies holding the dies in alignment during the vertical opening and closingmovement thereof, and a pair of horizontal presses, said presses being laterally spaced apart so as to exert forces on spaced horizontal axes and arranged so the axes are respectively at each side of the horizontally movable dies and acting respectively on said guides to move the horizontally movable pair of dies toward the other pair to upset the billet.

12. Apparatus for end and crosswise forging of a billet comprising a vertical press having vertically separable platens and vertical strain members at each side of the platens, a pair of horizontal presses, said presses being laterally spaced apart so as to exert forces on spaced horizontal axes and arranged so the axes are respectively at each side of the vertical press, said presses having frames extending laterally outward from the respective sides of the vertical press, rams on the frames at the inner ends thereof, compression members on the frames at the opposite ends thereof, and tension members on the frames intermediate the rams and compression members, said tension and compression members extending crosswise of the vertical strain members.

l3, Forging apparatus comprising a pair of dies having spaced opposed faces closable against each other by relative movement of the dies in a direction normal to the opposed faces, said dies when closed cooperating to define a cavity having an axis normal to the direction of opening and closing movement of the dies, guides at one end of the dies and on each side of the axis of the cavity and extending in the direction of opening and closing movement of the dies cooperating with the dies to maintain the dies aligned during opening and closing thereof, other guides for the dies extending in the direction of the axis of the cavity, press means cooperating with the other guides for closing the dies, and press means on each side of the axis of the cavity and at said one end of the dies cooperating with the first guides to move the dies along the axis of the cavity.

14. Apparatus for performing a single operation including forging both endwise and crosswise of the longitudinal axis of a billet, comprising die blocks movable crosswise of the axis of the billet to forge the billet crosswise of its axis, a press acting in a direction crosswise of the longitudinal axis of the billet for moving the die blocks to forge the billet in a crosswise direction, upsetting die means movable endwise of the longitudinal axis of the billet to upset the same, and a pair of presses acting on spaced axes parallel to the longitudinal axis of the billet for engaging said upsetting die means at each side thereof for moving the upsetting die means along the longitudinal axis of the billet to upset the same.

15. The method of forging a crank shaft from a billet having a portion to be formed into a crank pin, portions laterally spaced from each end thereof to be formed into journals, and intermediate portions connecting the pin and journal portions to be formed into webs or crank throws which comprises gripping the journal portions of the billet between journal forming dies under pressure crosswise of the journals, moving the pin portion of the billet in the direction to offset the same while maintaining the gripping pressure on the journal dies and moving The journal dies and the journal portions of the billet gripped between the dies endwise toward each other along the axis of the shaft, the movements being related such that the distance between the adjacent ends of the pin and journal portions of the crank along the center line of the billet remains constant during forging whereby the neutral axes of the web portions are substantially neither stretched nor compressed.

16. The method of. forging a crank shaft from a billet having a portion to be formed into a crank pin, portions laterally spaced from each end thereof to be formed into journals, and intermediate portions connecting the pin and journal portions to be formed into webs or crank throws which comprises, gripping the journal portions of the billet between journal forming dies under pressure crosswise of the journals, moving the pin portion of the billet in the direction to offset the same while maintaining the gripping pressure on the journal dies and moving the journal dies and the journal portions of the billet gripped between the dies endwise toward each other along the axis of the shaft, the rate of movement of the journal portions of the billet being substantially at the rate of movement of the pin portions of the billet times the tangent of the angle between the web and journal portions of the billet.

References Cited in the tile of this patent UNITED STATES PATENTS 510,103 Thomas et al. Dec. 5, 1893 624,019 Harrington May 2, 1899 2,534,613 Meley Dec. 19, 1950 SM" n. 

